Vertical Door Fan Shutter

ABSTRACT

A fan shutter having one end attachable to an exhaust fan and the opposite inlet end having a pair of vertical doors that are biased to close when the fan is off and to open by the force of vacuum when the fan is on. The use of vertical doors prevents the accumulation of dust and dirt on the doors. The vertical doors pivot horizontally in a housing that may have any desired shape, including a tubular shape with a bell mouth. The tubular bell mouth shutter design further provides improved air flow characteristics and decreased stress on the exhaust fan, compared to conventional fan shutters.

TECHNICAL FIELD

The present invention relates generally to the field of fan shuttersand, more particularly, to fan shutters having a vertical orientationand which prevent air flow through a fan when the fan is off.

BACKGROUND ART

Buildings often have ventilation systems for the exchange of air betweenthe building and the outside. These ventilation systems are usuallycomplex and are connected to the air handling or heating and airconditioning system of the building. Other ventilation systems are lesscomplex and are merely for exhausting stale air from the building, forintroducing fresh air into the building, or for basic temperatureregulation by exhausting hot or cold air from the building as necessary.

Various shutters, dampers, and closure panels for fans are known toregulate the exchange of air between the inside and outside of abuilding. For example, a series of horizontal louvers can be constructedto remain closed when the fan is off, but are pulled open by the airflowwhen the fan is on. A disadvantage of horizontal louvers is that dustbuilds up on the louvers, impeding their operation and airflow. Shuttersconstructed like a window shade roll down when the fan is off and rollup when the fan is on. A disadvantage of rolling shutters is that thereare many mechanical and electrical parts that can fail or are difficultto maintain.

The general use of automatically opening and/or closing louvers, vents,and doors in connection with fans or other forced air systems is wellknown, including the use of the weight of the door alone, or the use ofa counter weight to keep the door open or closed, or the use of stringand pulley systems.

U.S. Pat. No. 6,533,656 to Hertel discloses a counterweighted cover foran air handling system duct. This is a horizontal closure to fit over anoverhead or surface mounted duct vent. Forced air opens the cover, andwhen the forced air stops, the counterweight pivots the cover closed.U.S. Pat. No. 6,203,423 to Craw discloses a typical structure for avertical damper flap. This is a gravity driven flap that is opened byforced air and closes by gravity when the forced air flow stops. U.S.Pat. No. 6,183,359 to Klein discloses a typical structure for ahorizontal register flap. This is a gravity driven flap that is openedby forced air and closes by gravity when the forced air flow stops. U.S.Pat. No. 6,183,359 to Klein discloses a typical structure for ahorizontal register flap. This is a gravity driven flap that is openedby forced air and closes by gravity when the forced air flow stops.

U.S. Pat. No. 6,061,968 to Zimmerman discloses a hinged door assemblycomprising a weight to keep the door opened and a string/pulley/motorsystem to close the door. When it is desired to open the door, the motorunwinds the string and the weight, and the weight of the door opens thedoor. To close the door, the motor is reversed, winding the string. U.S.Pat. No. 5,921,862 to Ucciardi discloses a horizontally mounted doorflap for use on the discharge opening of a fan. The forced air from thefan forces the door open and when the Forced air flow stops, the weightof the door causes the door to close by gravity. The door has acounterweight to make it easier for the door to remain open.

U.S. Pat. No. 5,567,114 to Wallace discloses a typical structure for acounterweighted door for closing a downwardly oriented fan outlet. Thisis a gravity driven flap that is opened by forced air and closes by theweight of the counterweight when the forced air flow stops. U.S. Pat.No. 5,195,927 to Raisanen discloses an intake vent for a barn. Thedescribed advantages of this vent include its ability to be mounted oneither side of a wall and a counterweight for keeping the vent closed.U.S. Pat. No. 4,850,265 to Raisanen discloses a cupola mounted air ventfor a building having a structure for baffling rain. This device alsohas counterweights for keeping the vent closed.

U.S. Pat. No. 4,047,328 to Kehl discloses a greenhouse structureincluding a cooling system comprising a horizontally pivotable vent flapheld closed by a string/pulley and counterweight. The vent flap ishinged at its bottom to the greenhouse wall and opens from the top whenthe air pressure in the greenhouse is greater than outside. The stringis attached to the top of the vent and is weighted to keep the ventclosed. U.S. Pat. No. 3,631,790 to Olsen discloses an automaticallyclosing louver. The louver has a horizontally mounted hinge and sitsdownstream of the air flow. The air flow opens the louver and when theair flow stops, the weight of the louver causes it to close. U.S. Pat.No. 3,363,531 to Kohlmeyer discloses a vent for an animal housecomprising a closure flap operated by a string/pulley device. Pullingthe string causes the flap to rotate open or closed.

U.S. Pat. No. 2,823,600 to Cole discloses a vent for use in an airconditioning system. The system comprises dampers that open and closedepending on whether a fan is on or off. When the fan is on, the pull ofthe air opens the dampers. U.S. Pat. No. 2,502,736 to Marcoe discloses ahorizontally hinged intake vent with a counterweight damper plate. Airpressure causes the vent to open and when the air pressure equilibrates,the counterweight causes the vent to close. U.S. Pat. No. 218,596 toTaber discloses a horizontally hinged damper that opens inwardly to aduct when the air pressure within the duct is lower than the airpressure outside of the duct, and is for use in a stovepipe. Acounterweight closes the vent when the air pressure equilibrates.

Animal houses, such as chicken houses must have exhaust ventilation.Large fans typically are mounted on one end of the chicken house to pullair out of the chicken house. When the fans are on, there must be asunimpeded an air flow through the fan as possible to allow for bothadequate ventilation and fan efficiency. When the fans are off, it ispreferable to prevent air from escaping from the chicken house and/orair entering the chicken house through the fan box. This is especiallytrue in the summer and winter to prevent the chicken houses frombecoming too hot (summer) or too cold (winter) and to prevent excessivecooling or heating costs. Fan shutters can be valuable in loweringheating and cooling costs and in providing a better environment for theinhabitants of the building.

Notwithstanding the use of known ventilation systems, there is need fora mechanically simple and relatively low cost fan shutter that does notrequire frequent maintenance and/or repair.

DISCLOSURE OF THE INVENTION

The present invention has a housing that fits over a fan on the interiorof a building. The back of the housing faces the fan. The front or inletof the housing has two vertical doors that swing horizontally and thatopen and close when the fan is turned on and off, respectively. Thehousing uses one or more mechanisms to keep the doors shut when the fanis off. In a first embodiment the top of the housing extends farther outthan the bottom of the housing so that the doors are not quite vertical,and the tops of the doors are biased outward relative to the fan. Thus,gravity makes the doors swing shut. When the fan is on, the vacuumcaused by the fan is sufficient to open the doors. In a secondembodiment a counter weight is attached by a wire to each door. Thecounter weight biases the doors toward a closed position. In a thirdembodiment a spring is built into the hinge of each door to bias thedoors toward a closed position. A combination of these mechanisms can beused to ensure the doors remain closed when the fan is off. The housingcan have a rectangular or triangular shape. Alternatively, the housingcan have a tubular shape with a bell mouth on the inlet side.

An advantage of the present invention is a fan shutter that is simple inconstruction, durable, and easy to construct.

Another advantage is a fan shutter that requires little maintenance.

Another advantage is a fan shutter that is inexpensive.

Another advantage is a fan shutter that prevents air flow across the fanwhen the fan is off.

Another advantage is a fan shutter that improves the performance andefficiency of an air moving device such as, for example, a fan.

Another advantage is a fan shutter that improves breeding productivityin a poultry house.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a front view of the fan shutter of the present inventionwherein the doors are mounted slightly less than vertical, using gravityfor door closure.

FIG. 2 is a side view of the fan shutter of FIG. 1 showing the front endof the housing tilting downward.

FIG. 3 is a side view of an embodiment in which the entire housing tiltsdownward.

FIG. 4 is a side view of the fan shutter wherein the doors are mountedvertical, using springs or counterweights for door closure.

FIG. 5 is a front view of the fan shutter with a tubular housing havinga bell mouth on the intake side of the housing, the doors being in aclosed position.

FIG. 6 shows the fan shutter of FIG. 5 with doors in an open position.

BEST MODE FOR CARRYING OUT THE INVENTION

While the following description details the preferred embodiments of thepresent invention, it is to be understood that the invention is notlimited in its application to the details of construction andarrangement of the parts illustrated in the accompanying drawings, sincethe invention is capable of other embodiments and of being practiced invarious ways.

FIG. 1 shows a front view of the fan shutter 10 of the presentinvention. Fan shutter 10 has a housing 11 that covers exhaust fan 24and that supports doors 17. Housing 11 has a top 12, a bottom 13 andsides 14. The front end (inlet side) 25 is, preferably, triangular inshape with a center post 16. Doors 17 are mounted pivotally to centerpost 16 with hinges 18. Doors 17 are biased to close the open front endof housing 11 when the fan is off. Doors 17 are biased in a closedposition, preferably, by the force of gravity. This is accomplished bymounting housing 11 vertically, but having the front end 25 tiltdownward slightly from vertical about 1 to 20 degrees. Alternatively,the housing can be mounted tilting downward slightly from vertical about1 to 20 degrees, while the front end 15 of the housing remains vertical.These features are shown in more detail in FIGS. 2 and 3. Because thedoors are mounted in a vertical orientation and rotate horizontally,they will close the openings of the front end of shutter 11 when the fanis off. Doors 17 contact front edges 15 of housing 11 upon completeclosure of the front end of housing 11. Front edges 15 prevent doors 17from swinging outside housing 11. Back end 26 of housing 11 is attachedadjacent to Fan 24 using tabs or flanges 19. Doors 17 can also be biasedusing counter weights 21 with cables 22, or with springs in the hinges18. Gravity, counterweights, or springs can be used separately or incombinations to bias door 17 in a closed position. When exhaust fan 24is turned on it creates sufficient vacuum to open the doors, even thoughthe doors are biased towards a closed position. The use of verticaldoors instead of horizontal louvers provides improved air flow and lessstress on the fan. In addition, vertical doors provide less surfaceopenings for the accumulation of dirt, compared to horizontal louvers.

FIG. 2 shows a side view of the fan shutter 10 shown in FIG. 1. The top12 of housing 11 extends further from the wall 23 than the bottom 13.Thus, front end 12 and center post 16 tilt downward, biasing the doors17 to close by the force of gravity when fan 24 is not operating. FIG. 3shows an alternate construction of housing 11, wherein the entirehousing 11 tilts downward but front end 25 remains vertical. Doors 17are also biased in the closed position by the force of gravity with thisconstruction.

FIG. 4 shows a side view of the fan shutter 10 of FIG. 1, except thatneither the housing 11 or front end 25 tilt downward. The entire housingis mounted precisely vertical. In this embodiment doors 17 are notbiased to close by the force of gravity. The doors can be biased withcounterweights 21 or springs in hinges 18 or both.

FIG. 5 illustrates an alternate embodiment of the present inventionwherein the housing is round. Fan shutter 30 has a tubular housing 31.The back end 36 of housing 31 fits over wall 35 in front exhaust fan 38.Front end 37 (inlet) of housing 31 has a bell mouth 32, and two verticaldoors 33 which are hinged directly to front end 37 of housing 31 athinge points 34. The bell mouth 32 and tubular shaped housing 31 allowair to flow more smoothly and evenly without turbulence compared torectangular units, improving the air flow and efficiency of exhaust fan38. The front end 37 of the housing 31 can be tilted as described inFIGS. 1-4, so that doors 31 are biased in a closed position by gravity.Accordingly, the doors 33 will remain shut when exhaust fan 38 is off.When exhaust fan 38 is on, the vacuum created by exhaust fan 38 willopen doors 33. Hinging of doors 33 at hinge points 34 can beaccomplished by pins or inserts on doors 33 extending into housing 31.Thus, vertical doors 33 will pivot horizontally at hinge points 34.Doors 33 can also be biased in a closed position by the use of springsat the hinge points 34, or by counterweights, as described in FIGS. 1-4.FIG. 6 shows the fan shutter 30 of FIG. 5 with doors 33 in an openposition. A one piece, unified, damper fan combination can beconstructed by having housing 31 and fan system 38 form a single unit.

The foregoing description has been limited to specific embodiments ofthis invention. It will be apparent, however, that variations andmodifications may be made by those skilled in the art to the disclosedembodiments of the invention, with the attainment of some or all of itsadvantages and without departing from the spirit and scope of thepresent invention. For example, the fan shutter can have curved edgesand corners for safety. Other pivot joints known in the art besideshinges can be used on the doors. In addition to the front edges of thehousing, other door stop mechanisms known in the art can be used toprevent the doors from swinging outside the housing and to insure thatthe doors seal the front end of the housing. A spring device can beadded in the center of the doors and counter levered over so that whenthe doors are open, while the fan is operating, they will not have anypressure against them. Any type of suitable material can be used for thecable to connect the counterweight to the door, including string, twine,cable, chain, rope, and the like. The fan shutter can be built to anysize to accommodate any size fan, and can be incorporated into the fanhousing to form a single unitary housing for the fan, fan motor,shutter, and related parts. The shutter housing can be round,elliptical, square, or otherwise, and the bell mouth can be used withany shaped housing. The front end of the housing can be flat (coplanarwith the fan) or round, instead of triangular. The front end of thehousing can have one or a plurality of doors. The fan shutter of thepresent invention can be made from any suitable materials such as, forexample, plastic, metal, wood, ceramics, fibers, glasses or acombination thereof.

It will be understood that various changes in the details, materials,and arrangements of the parts which have been described and illustratedabove in order to explain the nature of this invention may be made bythose skilled in the art without departing from the principle and scopeof the invention as recited in the following claims.

1. A fan shutter, comprising: a) a housing having one end attachable toa fan; b) said housing having an opposite end with one or more doorsattached pivotably and centrally to said opposite end of said housing;and c) said one or more doors biased to close said opposite end of saidhousing.
 2. The fan shutter of claim 1 wherein said one or more doorsare attached to a center post by hinges at said opposite end of saidhousing.
 3. The fan shutter of claim 1 wherein said one or more doorsare biased to close by gravity by said opposite end of said housingbeing tilted from vertical.
 4. The fan shutter of claim 1 wherein saidone or more doors are biased to close by gravity by said housing beingtilted downward while said opposite end of said housing remainsvertical.
 5. The fan shutter of claim 1 wherein said one or more doorsare biased to close by the use of one or more counterweights.
 6. The fanshutter of claim 1 wherein said one or more doors have hinges and arebiased to close by the use of springs in said hinges.
 7. The fan shutterof claim 1 wherein said housing is tubular.
 8. The fan shutter of claim7 wherein said opposite end of said housing has a bell mouth.
 9. The fanshutter of claim 8 wherein said housing and said fan form a single unit.10. The fan shutter of claim 1 wherein said opposite end of said housinghas a bell mouth.
 11. The fan shutter of claim 1 wherein said housingand said fan form a single unit.
 12. A fan shutter, comprising: a) ahousing having one end attachable to a fan and an opposite end havingone or more doors attached pivotably to a centerpost; and b) said one ormore doors being vertically oriented, biased to close said opposite endof said housing when said fan is not operating, and opening saidopposite end of said housing when said fan is operating.
 13. The fanshutter of claim 12 wherein said one or more doors are attached to saidcenter post by hinges.
 14. The fan shutter of claim 13 wherein said oneor more doors are biased to close by gravity by said opposite end ofsaid housing being tilted from vertical.
 15. The fan shutter of claim 13wherein said one or more doors are biased to close by gravity by saidhousing being tilted downward while said opposite end of said housingremains vertical.
 16. The fan shutter of claim 13 wherein said one ormore doors are biased to close by the use of one or more counterweights.17. The fan shutter of claim 12 wherein said one or more doors havehinges and are biased to close by the use of springs in said hinges. 18.A fan shutter, comprising: a) a tubular housing having one endattachable to a fan and an opposite end having a bellmouth and one ormore doors attached pivotably and centrally to said opposite end; and b)said one or more doors being vertically oriented, biased to close saidopposite end of said housing when said fan is not operating, and openingsaid opposite end of said housing when said fan is operating.
 19. Thefan shutter of claim 18 wherein said one or more doors are biased toclose by gravity by said opposite end of said housing being tilted fromvertical.
 20. The fan shutter of claim 18 wherein said one or more doorsare biased to close by gravity by said housing being tilted downwardwhile said opposite end of said housing remains vertical.
 21. The fanshutter of claim 18 wherein said one or more doors are biased to closeby the use of one or more counterweights.
 22. The fan shutter of claim18 wherein said one or more doors have hinges and are biased to close bythe use of springs in said hinges.
 23. The fan shutter of claim 18wherein said housing and said fan form a single unit.